Magic Genes in Harry Potter?
by Hapcelion
Summary: I remember reading about how, in the Harry Potter Universe, Magic came about through having the right genes. So... I decided I wanted to write a little something about them, and I'd like to see what people think...


Alright, for those of you who have no interest in biology/genetics, I'd suggest not reading this part:

From official sources, the Magic Gene in the Harry Potter Universe seems to occupy a distinct locus within the human genome.

However, I've been having a bit of trouble pinpointing the certain mechanisms that control the presence the gene and the activation of its alleles.

While Mrs. Rowling has pointed out that the Magic Gene is Dominant, it might be more accurate to say that the Gene controlling for Magical Capabilities has allele _M_ (let's say for Magic, which is dominant. Recessive allele _m_ will be for Muggles.

For those who don't know, a gene is DNA sequence at a specific locus on the overall chromosome/genome that can control a phenotype (the characteristics of an organism that can be observed in life). However, there are alleles (different forms of a gene) that determine the actual character. Alleles are basically like socks. Your feet (in lieu of a gene) needs socks, but it has a variety of socks to choose from, say, one brown and one black. Provided, of course, that you are a normal human being with one allele from your mother and one from your father.

Genes code for proteins/RNAs, so we can assume that since _M_ is functioning with magic and _m_ cannot, there must be something about _m_ that prevents the protein or RNA for magic from being synthesized. Or maybe _m_ just doesn't make the right product to produce magic.

As another example, Gene A may control for Hair colour, but you'd need the _B_ allele to produce hair with Black pigments. Allele _b_, however, can encode for brown hair instead. Whichever one of them shows up depends on which one is dominant over the other. If Black is dominant over Brown, black shows up. Of course, there are cases of CoDominance, where some alleles may both be expressed at the same time, such as blood type AB, where protein types A and B are both created and embedded in a blood cell.

In terms of inheritance, things seem to follow, for the most part, simple Mendelian Genetics. Gregor Mendel, an Austrian monk from the 19th Century, studied pea plants and how they inherited their petal colours. The dominant allele colour was purple, while the mutant allele coloured white. Having a pure purple plant _PP_ cross bred with a pure white plant _pp_ would yield all purple plants of genotype _Pp_. Subsequent generations of _Pp_ cross bred with each other would lead to a ratio of three purple (_PP_, _Pp_) to one white (_pp_).

Snapdragons, however, will have a case of incomplete dominance, where the allele for red petals is technically dominant over the allele for white petals (which doesn't create proteins/RNA for colour in the first place). A mix of Red and White alleles will result in pink flowers.

In the Harry Potter Universe, while the Wizards inherit the allele M (probably _Mm_ or _MM_), that would mean having a Squib (hypothetically _mm_) would mean he'd also be a muggle (also _mm_). According to Mrs. Rowling's site, Squibs can only interact with the magical world with the help of certain magical objects and creatures. Muggles, I'm assuming, could also interact with them if given these things as well.

Now, about Muggle-Born magic users. If the Magic Capable Allele were dominant, it would have to show up in the first, second, or third generations at the least. If it isn't received by the children, then it's not getting passed on. But the fact is that they do get passed on and don't show up for many generations. This kind of disqualifies the Mendelian side of things.

How to explain this?

The subject of Epistasis involves the interaction between two or more genes at different loci can affect the phenotypic outcome. Again, hair colour, can be brown or black by virtue of the gene for hair colour, but the gene controlling the expression of hair colour can still be switched off, and the resulting hair becomes white.

Therefore, the Magic Gene probably has a Control Gene somewhere nearby, which explains why. For most Muggles, this Control Gene is most likely responsible for inactivating the Magic Gene. Once in a while, though, a defect in the Control Gene will allow for the Magic Gene to express itself. Or maybe it's just that the Control Gene has a pair of alleles that shuts it down (Dominant _O_ allele for On and recessive _o_ allele for Off). Other Magic users will most likely have their Control Genes turned off by the same _oo_ set, so they'll most likely have a pretty good wizarding family coming along. Keep in mind, mutations can still occur and may even turn an _o_ allele into an _O_ allele. Perhaps, then, some Muggle-Born's parents' genes could have _m_ mutate into_ M_ sometime in their lives.

As an additional thought, I was thinking of an allele for the Magic Gene that expresses Resistance to Magic, _m+_. With this particular Dominant allele (with respect to _m)_, the organism is likely to take a reduced affect from spells/charms/hexes/jinxes/etc. Of course, a Killing spell is going to leave them the same as it would anyone else, but the overall benefit is still pretty sweet. This could allow for the person holding the allele to physically go to Hogwarts and live to tell about it (because Obliviate only works for so long on the person with this allele in affect).

Either that, or a brand new gene for Magic Resistance. I think I'll call it _magR_.


End file.
